My scope fix and rebuild page,  plus my way to do calibration lacking $3000 in CAL gear (like Wes Hayward teaches, W7ZOI).("Wes" would use a calibrated scope )

The far better scopes to buy are here.

Why own a scope?, if you must ask?, then you do not need one!  (it is indispensable for diagnosis of all electronics, Hams that do repairs or HOME BREW GEAR)
These first 4  low bandwidth scopes. not one can see 30mhz, clearly.  2mHz, and 4 below, the Heath is 8mHz.(hopeful and ok for simple monitor)
None are calibrated,  (means 1v can be 2v) most ,back when, were aimed at TV work and audio (HI-FI) (read , crude)
RF work? not really... but... are ok as a crude RF monitor,  sure.  (30 mhz RF on  2mhz scope presents a green block of  raster,turn the GAIN KNOB high, ah,  a green blob...)

But can be used of peaking a signal or nulling one (like the  SSB carrier nulling steps in the manual)
If you can see the signal at all (try?) then it can be used, for many things,but not all things. Its best to have a scope that matches, your Gear (say your Ham radios and transmitters) or for all your gear.
I want to look for distortions, in my signals, but that takes BANDWITH.
These Anchors will not sync, on  your signal. ever. most are 400kz limits there.  In fact you might only see a glowing bar, for RF, signals.
The only old  TUBE scopes worth cash (IMHO) is on the right below, the HEATH, if you must.... (has nice books, and parts that can be found)
Best is to avoid tube scopes. use them as museum pieces. ( just my opinion, worth 2cents)
Best of all , buy a GOOD boat anchor, a TEK scope, the newer the better, mine was $50 ,bought from the TELCO auction. (465 working "solid state" but has a  CRT) there is nothing wrong with CRT's! not at all.
The 464 scope (TEK) is 100mhz, V and H, and can sync on 1nS single pulse,  (takes skill , but can, do)  repetivive pulses are  cake walk to see. 465 series can range up to 250Mhz.  475, 485s and more.
All techs. in 1970 (FYI) would tell you , the 465 is best all around scope for the money. It was. and still is.  (so far in 20 years mine has only shorted one cap inside, super easy find, and an easy fix)
The 465 was noted for its fantastic trigger, circuitry,  most scopes at the time were horrid in this regard. (
 It can trigger off a nano second glitch, in fact i've found those glitches in many top equipment (failing),  and used this scope to find the source. (every time)
Tek does make the best scopes, then and now.  But my OWON  is good too.
Buy a used Tek scope and avoid the super old ones with tubes, IMO.
The one on the right has some hope after restoring it too. The small MIL scope below is OS8  and is hopeless 2mhz,  (avoid all 1930s to 1950s scopes) find newer ones.  Avoid tubes. (move up to at least transistors !)

The TANK below , its not a boat anchor its really a Sherman TANK. scans cannon. (talks 2 men and a small boy to move!)
Watch "Christmas Vacation with Chevy Chase." See his wife plug in the exention cord and the Power Authority, putting 1 more NUKE on line,  the below scope, same deal. It sucks nearly 2000 watts.  doing little.
This is the 545B TEK 50mhz TANK, that I learned on, (not counting Mil gear)  and avoid this.
This 545 scope draws 16amps off the AC line and blows most circuit breakers in homes.  not fun, that... "gee do we have 20amp service around here??"
The above scope in use (a great scope in its own right), will keep the radio shack hot full time, no need to heat the room ever, (on) Check out the neat design, used by Tek, no parts wired willy-nilly, all neat in a row, brilliant work. IMO.
No lie, a great scope at its time. avoid it.
 I spent a good part of life behind this. (nostalgia) 250mhz 4 channels, and super stable, and accurate. (after cal) It's near the size of the 545 but lighter, and low current draw.  And a vast array of plug-in,  super useful.

You can RTM read for fun some old scope manuals here!

Better scopes are plentful;  VAST in fact.
As a rule Tektronix is best, HP 2nd. other, not so good.  (a high 5 to Philips if partrs can be found )
All scope after 1985 are best, older can be tubes. Avoid all tube scopes unless a year restoring one sounds like fun.  Some parts are not to be found.
There are great older transistor scopes, but if you can upgrade to newer scopes that have autocalibrtion built in,  (you will never be sorry)
Scopes with Tek 2xxx  series in the name are good.1982 to 1993, as are 24xx series scope later then TDS was born.
The TAS 464 digital? is very offordable. $75 to $100 sold all the time on fleabay.  ( a great place to start is here, not those over priced anchors above.)

The TEK,,,,,TBS anything, even new TBS, as seen here for as low as $450 "NEW"

There are nice OWON SDS DSO scopes too.   71xx series.

So are, all Tek DSO scopes, of any kind (but mine below)
My  2430 DSO (first) scope below top is good, I don't recommend it, but mine works like new.  (and autocals like a champ) But the full story by me is here.
This  2430 scope can not be fixed in many  cases (overheated by  fan blocked or dead fan).(amp modules not made now, RIP)  There are lots of $50 scopes , 1/2 can be fixed, more if you buy 2, the same.
465 is on bottom restored, and with LED, is and all transistor and IC (common) scope.  475, 485 all good.

$300 ? or so...Less used
OR FFT mode above scope, see IMD here?

What can I do or measure  with my scope. ? (HUGE Versatility !)
  1. The real waveform, voltage over time or even current over time, with a current probe.
  2. Voltages. A.C or D.C or moving fast. I can read and compute power,  voltage  RMS  , Peak or Peak to Peak.. (my DSO can even compute RMS of non sine wave signals)
  3. I can measure frequency,  the above DSO, the internal processor reads it on digitally.  (like 7.02051mhz) So is a FREQ Counter for free, inside, (its just software there doing that magic)
  4.   can measure power-supply ripple or noise, or worse and oscillating supply,
  5.   can see just about any noise on anything I want in my Receiver or transmitter.  With the FFT button I can see parasitic oscillation noises in my transmitter.
  6.   can diagnose logic gates,. 1 at a time,  and see noise here too.
  7.   can see and find glitches, that causes logic to go nuts.
  8.   can measure delays. (any) up to bandwidth and ranges offered.
  9.   can measure rise times and fall times, I can measure, what hams call,  attack , sustain and decay.  (rise time, duration and fall times)
  10. I can diagnose almost any class failure of any electronics,  limited only to the bandwidth and ranges of my scope, and all things that a logic analyzer can not find. (due to a first order class failures
  11. The DSO allows me to capture a signal then play with it, I can change the time base after the event, I can also save the screen to files, (pictures) I can roll TIME forward and back , limited only by memory size inside scope.
  12. With 2 channels you can see timing errors between the 2 inputs, say you are watching logic, and find the data is ok, but a clock is late, making the tested logic, fail to shift states.
  13. You can measure phasing errors.  that is enough, take a TEK class on scopes, there are many and all are free.
  14. We use it to do home brew gear (design of any kind) , testing prototypes, for diagnosis and repairs.  With out one, you work blind, or pray your "Pspice" matches, REALITY?
  15. Most scopes can work for a simple Ham radio  RF monitor. (or see audio signals any) RF below 50mhz?  Above 50, you'd need to pop for say $100
Scopes are really 3 things inside, the channel amp.'s (and BW) the sweeper gen, and Band-ranges, and  thetrigger section.  If one fails, to work doing what you want to do, then you will not be happy.
My buddy says if not Happy? , lower expectations... hihi
I write this only in the mode, that I've no idea what you need,  with generic  answers.

Keep in mind scopes can be found that cost $25,000 (for microwave work)
What we do is buy one that matches what we need, and no more. (or need to be rich)
Most modern scopes today have an A/D flash converter, 1/10th of an inch behind the front BNC jack pin, making the scope a pure digital processed machine."100% pure" Just like SDRs , are becoming,... now..
(this is the most easy way,  my 2430 does it the most hardest way possible, DEEP INSIDE, and because there was  no other ways existing  in 1985,  and amazing feat by TEK )!

The simple answer is, say  your  $3000 radio broke, unlike a toaster,  you don't throw it away, someone fixes it. 

Best read,  is "Experimental Methods in RF DESIGN" K7ZOI (ARRL) book." out of print  can be found. (got mine at ABE's books)
 (cost me 1 potted plant,) Read chapter 7, and your view of the world changes. (what can be done with a scope and why not to own a $2000 or near signal generator)
The chapters on DSP, are good too.

version 2.  9-30-2016